In recent years, on the basis of developing personal mobile apparatus, electric vehicle and green energy, the research related to energy storage device-battery tends to become more and more essential. In the field of car-used battery, user has to get over relative information about battery precisely for driving safety. The most vital part is to know well as regard to remained electrical capacity and health state of the battery so far for making the user of electric vehicle knowing about the timing of cut-off charging, cut-off discharging and replacement of the battery.
The present electrical capacity estimation technologies for battery include discharge test, open circuit voltage measuring, internal resistance measuring, loaded voltage measuring, electrolyte concentration measuring, coulomb counting method and so on. However, there are many factors that affect charge-discharge characteristics of the battery, in addition, various types of batteries possess different charge-discharge characteristics respectively. Therefore, except an estimation circuit design aimed at one single type of battery, if we anticipates the estimation circuit to achieve high accuracy and adaptive to multi types of batteries, high cost is needed. Additionally, mentioned estimation circuit must accomplished by application-specific integrated circuit. Thus, it is difficult to apply to portable mobile device.
Besides, the energy release for the battery is to convert chemical energy into electrical energy and discharge to a load. Theoretically, as long as a normal rated current 2000 mAh battery has a discharging current of 2 A, the discharge may last for 1 hour. The same reason, the discharging current of 1 A may discharge continuously for 2 hour. Actually, the chemical reaction speed inside the battery cannot offer required capacity of electric energy in time. Therefore, once the discharging current is increased, the total capacity the battery provides is decreased, which is called as Multiplier Effect. Owing to Synergic Effect, the battery discharges by a synergic-effect current that is larger than previous discharging current. The multiplier-effect current is also named recovery current. Once prior art estimates battery state of charge by discharging current-time integration, the estimating charge/discharge state of charge value is smaller than actual state of charge value caused by current multiplier-effect. That is to say, although a detecting circuit indicates that the battery is charged incompletely in charging condition, actually the battery is already overly charged. Oppositely, although the detecting circuit indicates that the battery has sufficient electrical-capacity in discharging condition, actually there is no remained electrical-capacity for the battery.